Fabricating method of electrode assembly and electrochemical cell containing the same

ABSTRACT

A fabricating method of an electrode assembly according to the present invention includes forming a radical unit having a four-layered structure obtained by stacking a first electrode, a first separator, a second electrode, and a second separator one by one, and stacking at least one radical unit one by one to form a unit stack part.

FIELD OF THE INVENTION

The present invention relates to a fabricating method of an electrodeassembly manufactured by a stacking method other than a folding method,and an electrochemical cell containing the same.

BACKGROUND OF THE ART

This application claims the priority of Korean Patent Application No.10-2012-0055074 filed on May 23, 2012, and Korean Patent ApplicationNo.10-2013-0058165 filed on May 23, 2013, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

A secondary battery attracts attention as a power source of an electricvehicle (EV), a hybrid electric vehicle (HEV), a parallel hybridelectric vehicle (PHEV), and the like, which have been suggested asalternatives for solving defects such as environmental contamination dueto commonly used gasoline vehicles, diesel vehicles, and the like usingfossil fuels. In a medium and large size device such as automobiles, amedium and large size battery module in which a plurality of batterycells is electrically connected is used due to the need of high powerand high capacity.

However, since the medium and large size battery module is necessary tobe manufactured so as to have a small size and a light weight, a squareshape battery, a pouch shape battery, etc., which may be stacked in ahigh degree and have a light weight when compared with the capacity, arewidely used as the battery cells of the medium and large size batterymodule.

Generally, an electrode assembly may be classified according to thestructure of the electrode assembly having cathode/separator/anode.Typically, the electrode assembly may be classified into a jelly-roll (awrapping type) electrode assembly, in which cathodes and anodes havinglong sheet shapes along with an interposed separator are wrapped, astack type (a laminated type) electrode assembly, in which a pluralityof cathodes and anodes along with interposed separators, which are cutinto specific size units and stacked one by one, and a stack/foldingtype electrode assembly. The stack/folding type and the stack typeelectrode assemblies are typically used, and defects on each structurewill be explained.

First, the stack/folding type electrode assembly disclosed in KoreanPatent Application Publication Nos. 2001-0082058, 2001-0082059 and2001-0082060 filed by the present Applicant will be explained.

Referring to FIG. 13, an electrode assembly 1 of a stack/foldingstructure includes a plurality of overlapped full cells 2, 3, 4 . . .(Hereinafter, will be referred to as ‘full cell’) as a unit cells, inwhich cathode/separator/anode are positioned in sequence. In each of theoverlapped parts, a separator sheet 5 is interposed. The separator sheet5 has a unit length possibly wrapping the full cells. The separatorsheet 5 initiated from the central full cell 10 is bent inward by theunit length while continuously wrapping each of the full cells to theoutermost full cell 14 so as to be interposed in the overlapped parts ofthe full cells. The distal end portion of the separator sheet 5 isfinished by conducting heat welding or attaching using an adhesion tape6. The stack/folding type electrode assembly is manufactured by, forexample, arranging the full cells 2, 3, 4 . . . on the separator sheet 5having a long length and wrapping from one end portion of the separatorsheet 5 in sequence. However, in this structure, a temperature gradientmay be generated between the electrode assemblies 1 a, 1 b and 2 in thecenter portion and the electrode assemblies 3 and 4 disposed at theouter portion to produce different heat emitting efficiency. Thus, thelifetime of the electrode assembly may be decreased when used for a longtime.

The manufacturing process of the electrode assembly is conducted byusing two lamination apparatuses for manufacturing each electrodeassembly and one additional folding apparatus as a separate apparatus.Therefore, the decrease of the tack time of the manufacturing processhas a limitation. Particularly, the minute aligning of the electrodeassemblies disposed up and down is difficult in the structureaccomplishing the stacked structure through the folding. Thus, themanufacture of an assembly having a reliable quality is very difficult.

FIG. 14 illustrates the structures of A type and C type bicellsdifferent from the full cell structure as a unit cell applicable in theabove-described folding structure in FIG. 13. At the center portionwhich is an initiating point of wrapping among the overlappedelectrochemical cells applicable in the present invention, a bicellhaving a cathode/separator/anode/separator/cathode structure (a) (A typebicell), or a bicell having a anode/separator/cathode/separator/anodestructure (b) (C type bicell), surrounded by a separator sheet isdisposed. That is, the structure of a common bicell may be accomplishedby ‘A type bicell’ having a stacked structure of a double sided cathode10, a separator 20, a double sided anode 30, a separator 40, a doublesided cathode 50 one by one as illustrated in FIG. 14 (a), or a stackedstructure of a double sided anode 30, a separator 20, a double sidedcathode 10, a separator 40, and a double sided anode 50 one by one asillustrated in FIG. 14 (b).

For the structure of the electrode assembly using the folding process, afolding apparatus is separately necessary. When a bicell structure isapplied, two types of the bicells of the A type and the C type, aremanufactured and stacked. Before conducting the folding, the keeping ofthe distance between one bicell and another bicell disposed on a longseparator sheet is a very difficult task. That is, an accurate alignmentbetween the upper and lower unit cells may be difficult. Whenmanufacturing a high capacity cell, a considerable time may be necessaryfor changing the types.

Next, a stack type electrode assembly will be explained. Since the stacktype electrode assembly is widely known in this art, only on the defectsof the stack type electrode assembly will be explained in brief.

Generally, in the stack type electrode assembly, the length and thewidth of a separator are greater than those of an electrode. Theseparator is stacked on a magazine or a jig having corresponding sizewith respect to the length and the width of the separator, and thestacking process of the electrode on the separator is repeatedlyconducted to manufacture the stack type electrode assembly.

However, when the stack type electrode assembly is manufactured by theabove-described method, the electrode and the separator are necessary tobe stacked one by one. Thus, the working time is increased to remarkablylower the productivity. In addition, the alignment of the plurality ofthe separators by the length and the width is possible. However, sincethe magazine or the jig accurately aligning the electrodes put on theseparator is not present, the plurality of the electrodes provided inthe stack type electrode assembly may not be aligned but may bedislocated.

In addition, since the faces of the cathode and the anode across theseparator are dislocated, an electrochemical reaction may not be made ina portion of the active material region coated on the surfaces of thecathode and the anode. Thus, the efficiency of a battery cell may bedeteriorated.

SUMMARY OF THE INVENTION

An aspect of the present invention considering the above-describeddefects, provides a fabricating method accomplishing the maximization ofsimplifying a process and a cost reduction by manufacturing a unit cellhaving a radical unit structure, deviated from the unit cell of the A orC type bicell structure, which is applicable in the folding process, andby manufacturing a secondary battery through conducting only a stackingprocess other than a folding process.

According to an aspect of the present invention, there is provided afabricating method of an electrode assembly including forming a radicalunit having a four-layered structure obtained by stacking a firstelectrode, a first separator, a second electrode, and a second separatorone by one, and stacking at least one radical unit one by one to form aunit stack part.

Further, the method may further include a step of stacking a firstauxiliary unit on a first distal end electrode which is the firstelectrode positioned at the uppermost or the lowermost portion of theunit stack part, and a step of stacking a second auxiliary unit on asecond distal end electrode which is the second electrode positioned atthe uppermost or the lowermost portion of the unit stack part.

In addition, the method may further include a step of fixing by tapingthe side portion or the front portion of the unit stack part by using apolymer tape.

EFFECT OF THE INVENTION

According to the fabricating method of an electrode assembly of thepresent invention, radical units may be minutely aligned and theproductivity may be increased.

In addition, according to the fabricating method of an electrodeassembly of the present invention, a coating material is coated only onone side of a second separator facing a second electrode, and a costreduction effect may be large.

In addition, according to the fabricating method of an electrodeassembly of the present invention, only a step of stacking a firstauxiliary unit and a second auxiliary unit including only one coatedlayer of an active material layer at the outermost portion on a unitstack part is included, and the waste of the active material layer maybe prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a side view illustrating a first structure of a radical unitaccording to the present invention;

FIG. 2 is a side view of a second structure of a radical unit accordingto the present invention;

FIG. 3 illustrates a process for manufacturing a radical unit accordingto the present invention;

FIG. 4 is a side view illustrating a first structure of a unit stackpart including a radical unit and a first auxiliary unit according tothe present invention;

FIG. 5 is a side view illustrating a second structure of a unit stackpart including a radical unit and a first auxiliary unit according tothe present invention;

FIG. 6 is a side view illustrating a third structure of a unit stackpart including a radical unit and a second auxiliary unit according tothe present invention;

FIG. 7 is a side view illustrating a fourth structure of a unit stackpart including a radical unit and a second auxiliary unit according tothe present invention;

FIG. 8 is a side view illustrating a fifth structure of a unit stackpart including a radical unit, a first auxiliary unit and a secondauxiliary unit according to the present invention;

FIG. 9 is a side view illustrating a sixth structure of a unit stackpart including a radical unit and a first auxiliary unit according tothe present invention;

FIG. 10 is a side view illustrating a seventh structure of a unit stackpart including a radical unit and a second auxiliary unit according tothe present invention;

FIG. 11 is a flow chart illustrating a fabricating method of anelectrode assembly according to the present invention;

FIG. 12 is a conceptual diagram illustrating a fixing part of anelectrode assembly according to the present invention;

FIG. 13 is a conceptual diagram illustrating a folding structure of anelectrode assembly according to related arts; and

FIG. 14 is a side view illustrating A type and C type bicell structuresapplicable in the folding structure in FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings. However, the presentinvention is not restricted or limited to the following exemplaryembodiments.

A unit stack part (see 100 a in FIG. 4) includes at least one radicalunit (see 110 a in FIG. 1, etc.). That is, a unit stack part 100includes one radical unit 110 or at least two radical units 110 . Theunit stack part 100 is formed by stacking the radical units 110. Forexample, the unit stack part 100 may be formed by stacking one radicalunit 110 on another radical unit 110. As described-above, the unit stackpart 100 is formed by stacking the radical units 110 as a unit. That is,the radical units 110 are previously formed and then stacked one by oneto form the unit stack part 100.

As described above, the unit stack part 100 in accordance with thisexample embodiment has basic features in repeatedly stacking the radicalunits 110 for the manufacture thereof. Through manufacturing the unitstack part 100 by the above-described method, merits may be obtained,that the radical unit 110 may be minutely aligned, and the productivitymay be improved.

The radical unit 110 is formed by stacking a first electrode 111, afirst separator 112, a second electrode 113 and a second separator 114one by one. As described above, the radical unit 110 basically includesa four-layered structure. More particularly, the radical unit 110 may beformed by stacking the first electrode 111, the first separator 112, thesecond electrode 113 and the second separator 114 one by one from theupper portion to the lower portion as illustrated in FIG. 1, or may beformed by stacking the first electrode 111, the first separator 112, thesecond electrode 113 and the second separator 114 one by one from thelower portion to the upper portion as illustrated in FIG. 2. In thiscase, the first electrode 111 and the second electrode 113 have oppositeelectrodes to each other. For example, when the first electrode 111 isan cathode, the second electrode 113 is an anode. Of course, the reversecase may be possible.

The radical unit 110 may be formed by the following process (see FIG.3). First, a first electrode material 121, a first separator material122, a second electrode material 123 and a second separator material 124are prepared. In this case, the electrode materials 121 and 123 are cutinto a certain size to form the electrodes 111 and 113, which will bedescribed herein below. Similarly, the separator materials 122 and 124are cut into a certain size. For process automation, the electrodematerials and the separator materials may preferably have a wrappedshape on a roll. After preparing the materials, the first electrodematerial 121 is cut into the certain size by means of a cutter C₁. Then,the second electrode material 123 also is cut into the certain size bymeans of a cutter C₂. Then, the first electrode material 121 having thecertain size is supplied on the first separator material 122. The secondelectrode material 123 having the certain size also is supplied on thesecond separator material 124. Then, all of the materials are suppliedto laminators L₁ and L₂.

As described above, the unit stack part 100 is formed by repeatedlystacking the radical units 110. However, when the electrode and theseparator constituting the radical unit 110 are separated from eachother, the repeated stacking of the radical units 110 may be verydifficult. Thus, the electrode and the separator may be preferablyattached to each other when forming the radical units 110. Thelaminators L₁ and L₂ are used for attaching the electrode and theseparator to each other. That is, the laminators L₁ and L₂ apply apressure, or heat and pressure to the materials to accomplish theattachment of the electrode material and the separator material. Theelectrode material and the separator material are attached to each otherby means of the laminators L₁ and L₂. Through the attachment, theradical units 110 may maintain the shape itself more stably.

Finally, both of the first separator material 122 and the secondseparator material 124 are cut into a certain size by using a cutter C₃.Through the cutting, the radical units 110 may be formed. Various kindsof inspections may be additionally conducted with respect to the radicalunits 110. For example, inspections on thickness, vision, short, or thelike may be additionally conducted.

Meanwhile, the surface of the separator (separator material) may becoated with a coating material having adhesiveness. In this case, thecoating material may be a mixture of inorganic particles and a binderpolymer. The inorganic particles may improve the thermal stability ofthe separator. That is, the inorganic particles may prevent thecontraction of the separator at a high temperature. In addition, thebinder polymer may fix the inorganic particles. Thus, the inorganicparticles may include certain pore structures. Due to the porestructure, ions may smoothly move from the cathode to the anode, eventhough the inorganic particles are coated on the separator. In addition,the binder polymer may keep the inorganic particles stably on theseparator to improve the mechanical stability of the separator. Further,the binder polymer may attach the separator onto the electrode morestably. For reference, the separator may be formed by using apolyolefin-based separator substrate.

However, as illustrated in FIGS. 1 and 2, at both sides of the firstseparator 112, the electrodes 111 and 113 are positioned. However, onlyone electrode 113 is positioned at one side of the second separator 114.Thus, the coating material may be coated on both sides of the firstseparator 112, while the coating material may be coated on one side ofthe second separator 114. That is, both sides of the first separator 112facing the first electrode 111 and the second electrode 113 may becoated with the coating material, and one side of the second separator114 facing the second electrode 113 may be coated with the coatingmaterial.

As described above, the attachment by using the coating material may besufficient when accomplished within the radical unit . Thus, the coatingmay be conducted with respect to only one side of the second separator114 as described above. Merely, since adhesion among the radical unitsmay be accomplished by applying a method such as heat press, both sidesof the second separator 114 may be coated as occasion demands. That is,the coating material may be coated on one side of the second separator114 facing the second electrode 113 and on the opposite side thereof. Inthis case, the radical unit positioned at the upper portion and theradical unit positioned just below thereof may make an attachmentthrough the coating material on the outer surface of the secondseparator.

For reference, when a coating material having adhesiveness is coated onthe separator, the direct pressurization onto the separator by using anobject is not recommended. Generally, the separator is extendedoutwardly from the electrode. An attempt may be made to combine thedistal end portion of the first separator 112 and the distal end portionof the second separator 114 to each other. For example, an attempt forwelding the distal end portion of the first separator 112 and the distalend portion of the second separator 114 by means of sonication weldingmay be made. For the sonication welding, a target is necessary to bedirectly pressurized by using a horn. However, when the distal endportions of the separators are directly pressurized by using the horn,the horn may attach to the separator due to the coating material havingthe adhesiveness. In this case, the apparatus may be broken. Therefore,when the coating material having the adhesiveness is coated on theseparator, the direct application of the pressure onto the separator byusing an object is not preferable.

In addition, the radical unit 110 does not necessarily include thefour-layered structure. For example, the radical unit 110 may have aneight-layered structure formed by stacking the first electrode 111, thefirst separator 112, the second electrode 113, the second separator 114,the first electrode 111, the first separator 112, the second electrode113 and the second separator 114 one by one . That is, the radical unit110 may have a structure formed by repeatedly stacking the four-layeredstructure. As described above, the unit stack part 100 may be formed byrepeatedly stacking the radical units 110. Thus, the unit stack part 100may be formed by repeatedly stacking the four-layered structure, or theunit stack part 100 may be formed by repeatedly stacking, for example,the eight-layered structure.

Meanwhile, the unit stack part 100 may further include at least one of afirst auxiliary unit 130 and a second auxiliary unit 140. First, thefirst auxiliary unit 130 will be explained. The radical unit 110 isformed by stacking the first electrode 111, the first separator 112, thesecond electrode 113 and the second separator 114 from the upper portionto the lower portion, or from the lower portion to the upper portion,one by one . When the unit stack part 100 is formed by repeatedlystacking the radical units 110, the first electrode 116 (Hereinafter,will be referred to as ‘first distal end electrode’) may be positionedat the uppermost portion (see FIG. 1), or at the lowermost portion (seeFIG. 2) of the unit stack part 100 (the first distal end electrode maybe an cathode or a anode.). The first auxiliary unit 130 may beadditionally stacked on the first distal end electrode 116.

More particularly, as illustrated in FIG. 4, when the first electrode111 is a cathode, and the second electrode 113 is an anode, the firstauxiliary unit 130 a may be formed by stacking from the first distal endelectrode 116, that is, to the outer portion from the first distal endelectrode 116 (to the upper portion in FIG. 4), the separator 114, theanode 113, the separator 112 and the cathode 111 one by one. Inaddition, as illustrated in FIG. 5, when the first electrode 111 is theanode, and the second electrode 113 is the cathode, the first auxiliaryunit 130 b may be formed by stacking from the first distal end electrode116, that is, to the outer portion from the first distal end electrode116, the separator 114 and the cathode 113 one by one. As illustrated inFIGS. 4 and 5, in the unit stack part 100, the cathode may be positionedat the outermost portion of the first distal end electrode 116 due tothe first auxiliary unit 130.

Generally, an electrode includes a current collector and active materiallayers (active material) coated on both sides of the current collector.Thus, the active material layer positioned under the current collectoramong the active material layers of the cathode makes a reaction withthe active material layer positioned on the current collector among theactive material layers of the cathode in FIG. 4 through the separator.When the unit stack part 100 is formed by manufacturing the same radicalunits 110 and stacking thereof one by one, the first distal endelectrode positioned at the uppermost portion or the lowermost portionof the unit stack part 100 may include the active material layers onboth sides of the current collector as another first electrode. However,when the first distal end electrode has a structure including the activematerial layers coated on both sides of the current collector, theactive material layer positioned at the outer portion among the activematerial layers of the first distal end electrode may not make areaction with another active material layer. Thus, the wasting of theactive material layer may be generated.

The first auxiliary unit 130 is provided to solve the above-mentioneddefects. That is, the first auxiliary unit 130 is separately formed fromthe radical units 110. Thus, the first auxiliary unit 130 may include ancathode including the active material layer formed only on one side ofthe current collector. That is, the first auxiliary unit 130 may includean cathode including the active material layer coated only on one sidefacing the radical unit 110 (a side facing the lower portion in FIG. 4)among both sides of the current collector. Consequently, when the unitstack part 100 is formed by additionally stacking the first auxiliaryunit 130 on the first distal end electrode 116, the cathode includingthe coated layer only on one outermost side of the first distal endelectrode 116 may be disposed. Thus, the defects on the waste of theactive material layer may be solved. Since the cathode has aconstitution releasing, for example, nickel ions, the provision of thecathode at the outermost portion is preferred when considering batterycapacity.

Then, the second auxiliary unit 140 will be explained. The secondauxiliary unit 140 basically exhibits the same function as the firstauxiliary unit 130. More particularly, the radical unit 100 is formed bystacking the first electrode 111, the first separator 112, the secondelectrode 113 and the second separator 114 from the upper portion to thelower portion, or from the lower portion to the upper portion, one byone. When the unit stack part 100 is formed by repeatedly stacking theradical units 110, the second separator 117 (Hereinafter, will bereferred to as ‘second distal end separator’) may be positioned at theuppermost portion (see FIG. 2) or the lowermost portion (see FIG. 1) ofthe unit stack part 100. The second auxiliary unit 140 may beadditionally stacked on the second distal end separator 117.

More particularly, as illustrated in FIG. 6, when the first electrode111 is an cathode, and the second electrode 113 is a anode, the secondauxiliary unit 140 a may be formed as the cathode 111. In addition, asillustrated in FIG. 7, when the first electrode 111 is a anode, and thesecond electrode 113 is an cathode, the second auxiliary unit 140 b maybe formed by stacking from the second distal end separator 117, that is,to the outer portion of the second distal end separator 117 (to thelower portion in FIG. 7), the anode 111, the separator 112 and thecathode 113 one by one. The second auxiliary unit 140 may also includean cathode including an active material layer coated only one sidefacing the radical unit 110 (one side facing the upper portion in FIG.7) among both sides of the current collector as for the first auxiliaryunit 130. When the unit stack part 100 is formed by additionallystacking the second auxiliary unit 140 on the second distal endseparator 117, an cathode including a coated layer only on one sidethereof may be positioned at the outermost portion of the second distalend separator 117.

For reference, in FIGS. 4 & 5, and 6 & 7, stacked structures of thefirst electrode 111, the first separator 112, the second electrode 113and the second separator 114 one by one, from the upper portion to thelower portion, are illustrated. On the contrary, stacked structures ofthe first electrode 111, the first separator 112, the second electrode113 and the second separator 114 one by one, from the lower portion tothe upper portion, may be explained by the same manner as describedabove. The first auxiliary unit 130 and the second auxiliary unit 140may further include a separator at the outermost portion as occasiondemands. For example, when the cathode positioned at the outermostportion is necessary to be electrically insulated from a case, the firstauxiliary unit 130 and the second auxiliary unit 140 may further includea separator at the outermost portion of the cathode. For such reasons, aseparator may be further included in the cathode exposed to the oppositeside to the stacked portion of the second auxiliary unit 140 (theuppermost portion of the electrode assembly in FIG. 6).

Meanwhile, a unit stack part may be preferably manufactured asillustrated in FIGS. 8 to 10. First, a unit stack part 100 e asillustrated in FIG. 8 may be formed. A radical unit 110 b may be formedby stacking a first electrode 111, a first separator 112, a secondelectrode 113 and a second separator 114 from the lower portion to theupper portion, one by one. In this case, the first electrode 111 may bean cathode, and the second electrode 113 may be a anode. A firstauxiliary unit 130 c may be formed by stacking from the first distalelectrode 116, that is, from the upper portion to the lower portion asin FIG. 8, the separator 114, the anode 113, the separator 112 and thecathode 111, one by one. In this case, the cathode 111 of the firstauxiliary unit 130 c may include an active material layer formed only onone side facing a radical unit 110 b.

In addition, a second auxiliary unit 140 c may be formed by stackingfrom a second distal end separator 117, and from the lower portion tothe upper portion in FIG. 8, an cathode 111 (a first cathode), aseparator 112, a anode 113, a separator 114 and an cathode 118 (a secondcathode), one by one. In this case, the cathode 118 (the second cathode)positioned at the outermost portion of the second auxiliary unit 140 cmay include an active material layer formed only on one side facing theradical unit 110 b. For reference, the alignment of the units may beeasily conducted when the auxiliary unit includes the separator.

Then, a unit stack part 100 f as illustrated in FIG. 9 may be formed. Aradical unit 110 b may be formed by stacking a first electrode 111, afirst separator 112, a second electrode 113 and a second separator 114one by one from the lower portion to the upper portion. In this case,the first electrode 111 may be an cathode, and the second electrode 113may be a anode. A first auxiliary unit 130 d may be formed by stackingthe separator 114, the anode 113 and the separator 112, one by one froma first distal end electrode 116. In this case, a second auxiliary unitmay not be provided. For reference, a anode may make a reaction with analuminum layer of an electrode case (for example, pouch) due to apotential difference. Thus, the anode is preferably insulated from theelectrode case by means of the separator.

Finally, a unit stack part 100 g as illustrated in FIG. 10 may beformed. A radical unit 110 c may be formed by stacking a first electrode111, a first separator 112, a second electrode 113 and a secondseparator 114 from the upper portion to the lower portion. In this case,the first electrode 111 may be a anode, and the second electrode 113 maybe an cathode. A second auxiliary unit 140 d may be formed by stackingthe anode 111, the separator 112, the cathode 113, the separator 114 andthe anode 119 one by one from a second distal end separator 117. In thiscase, a first auxiliary unit may not be provided.

Referring to FIG. 11, a fabricating method of an electrode assemblyaccording to the present invention will be explained.

In the fabricating method of an electrode assembly according to thepresent invention, a step of forming a radical unit (S100) for forming aradical unit 110 having a four-layered structure formed by stacking afirst electrode 111, a first separator 112, a second electrode 113 and asecond separator 114 one by one, and a step of stacking the radicalunits for forming a unit stack part 100 (S200) by stacking at least oneradical unit 110 one by one are included. The explanation on the radicalunit 110 and the unit stack part 100 has been described above, and willbe omitted.

The fabricating method of an electrode assembly according to the presentinvention may further include a step of stacking a first auxiliary unit(S300) in which a first auxiliary unit 130 is stacked on a first distalend electrode 116, which is the first electrode positioned at theuppermost portion or at the lowermost portion of the unit stack part100. In addition, the fabricating method of the electrode assemblyaccording to the present invention may further include a step ofstacking a second auxiliary unit (S400) on a second distal end separator117, which is the second separator positioned at the uppermost portionor at the lowermost portion of the unit stack part 100. The explanationon the first auxiliary unit 130 and the second auxiliary unit 140 hasbeen described above, and will be omitted.

FIG. 12 illustrates an embodiment on using a fixing member for fixing aunit stack part according to the present invention.

A fabricating method of an electrode assembly according to the presentinvention may further include a fixing step (S500)by using a fixing partT1 for fixing the side portion or the front portion of the unit stackpart 100 including a stacked structure of the radical units 110. Thatis, in order to confirm the stability of a stacking structure, the unitstack part 100 may be fixed by using a separate member at the sideportion thereof. The fixing may be accomplished by taping only the sideportions of the unit stack part 100 as illustrated in FIG. 12( a), or byusing a fixing part T2 for fixing the whole sides of the unit stack part100 as illustrated in FIG. 12( b). In addition, a polymer tape may beused as the fixing parts T1 and T2.

Hereinafter, particular materials and constitutional features ofconstituent elements of the electrode assembly according to the presentinvention will be explained.

[Cathode Structure]

In the present invention, an electrode provided in a radical unit isclassified into an cathode and a anode and is manufactured by combiningthe cathode and the anode along with a separator interposedtherebetween. The cathode may be manufactured, for example, by coating aslurry of a mixture of an cathode active material, a conductive materialand a binder on an cathode current collector, drying and pressing. Afiller may be added into the mixture as occasion demands. When thecathode is accomplished as a sheet shape to be installed on a roll, themanufacturing rate of the radical unit may be increased.

[Cathode Current Collector]

An cathode current collector is generally manufactured to a thickness ofabout 3 to 500 μm. For the cathode current collector, a material notinducing the chemical change of a battery and having a high conductivitymay be used without limitation. For example, stainless steel, aluminum,nickel, titanium, clacined carbon, a surface treated material ofaluminum or stainless steel with carbon, nickel, titanium, silver, orthe like may be used. The adhesiveness of an cathode active material maybe increased by forming minute embossing on the surface of the cathodecurrent collector. The cathode current collector may have various shapessuch as a film, a sheet, a foil, a net, a porous material, a foamedmaterial, a non-woven material, and the like.

[Cathode Active Material]

An cathode active material for a lithium secondary battery may include,for example, a layered compound of lithium cobalt oxide (LiCoO₂),lithium nickel oxide (LiNiO₂), etc. or a substituted compound with oneor more transition metals; lithium manganese oxide such asLi_(1+x)Mn_(2-x),O₄ (in which x is 0 to 0.33), LiMnO₃, LiMn₂O₃, LiMnO₂,etc.; lithium copper oxide (Li₂CuO₂); vanadium oxide such as LiV₃O₈,LiFe₃O₄, V₂O₅, Cu₂V₂O₇, etc.; Ni site-type lithium nickel oxiderepresented by Chemical Formula of LiNi_(1-x)M_(x)O₂ (in which, M=Co,Mn, Al, Cu, Fe, Mg, B or Ga, x=0.01 to 0.3); lithium manganese complexoxide represented by Chemical Formulae LiMn_(2-x)M_(x)O₂ (in which M=Co,Ni, Fe, Cr, Zn or Ta, and x=0 .01 to 0.1) or Li Mn MO₈ (in which, M=Fe,Co, Ni, Cu or Zn) ; LiMn₂O₄ in which a portion of Li is substituted withalkaline earth ions; a disulfide compound; Fe_(z) (MoO₄)₃, and the like,without limitation.

Generally, a conductive material is added into a mixture including thecathode active material by 1 to 50 wt % based on the total amount of themixture. Any conductive material having conductivity without inducingthe chemical change of a battery may be used without limitation. Forexample, graphite such as natural graphite, synthetic graphite, etc.;carbon black such as carbon black, acetylene black, ketjen black,channel black, furnace black, lamp black, thermal black, etc.;conductive fiber such as carbon fiber, metal fiber, etc.; a metal powdersuch as a carbon fluoride powder, an aluminum powder, a nickel powder,etc.; conductive whisker such as potassium titanate, etc.; conductivemetal oxide such as titanium oxide, etc.; a conductive material such aspolyphenylene derivatives, etc. may be used

A binder is a component assisting the bonding of the active materialwith the conductive material and the bonding with the current collector,and is commonly included by about 1 to 50 wt % based on the total amountof the mixture including the cathode active material. Examples of thebinder may include polyfluoro vinylidene, polyvinyl alcohol,carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose,regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene,polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM),sulfonated EPDM, styrene butadiene rubber, fluorine rubber, variouscopolymers, etc.

A filler is a component restraining the expansion of the cathode and isselectively used. A material not inducing the chemical change of abattery and having a fiber phase may be used without limitation. Forexample, olefin-based polymer such as polyethylene, polypropylene, andthe like; fiber phase material such as glass fiber, carbon fiber, andthe like may be used.

[Anode Structure]

A anode may be manufactured by coating a anode active material on aanode current collector, drying and pressing. A conductive material, abinder, a filler, etc. may be selectively included as occasion demands.When the anode is formed as a sheet shape to be installed on a roll, themanufacturing rate of a radical unit may be increased.

[Anode current Collector]

A anode current collector is generally manufactured to a thickness ofabout 3 to 500 μm. For the anode current collector, a material notinducing the chemical change of a battery and having conductivity may beused without limitation. For example, copper, stainless steel, aluminum,nickel, titanium, clacined carbon, a surface treated material of copperor stainless steel with carbon, nickel, titanium, silver, analuminum-cadmium alloy, etc. may be used. Also, as for the cathodecurrent collector, the adhesiveness of the anode active material may beincreased by forming minute embossing on the surface of the anodecurrent collector. The anode current collector may have various shapessuch as a film, a sheet, a foil, a net, a porous material, a foamedmaterial, a non-woven material, etc.

[Anode Active Material]

A anode active material may include, for example, carbon such asnon-graphitizable carbon, graphite-based carbon, etc.; a metal complexoxide such as Li_(x)Fe₂O₃ (0≦x≦1), Li_(x)WO₂ (0≦x≦1),Sn_(x)Me_(1-x)Me′_(y)O_(z), (Me: Mn, Fe, Pb, Ge; Me′: Al, B, P, Si,elements found in Group 1, Group 2 and Group 3 in a periodic table,halogen; 0<x<1; 1≦y≦3; 1≦z≦8), etc.; a lithium metal; a lithium alloy; asilicon-based alloy; a tin-based alloy; a metal oxide such as SnO, SnO₂,PbO, PbO₂, Pb₂O₃, Pb₃O₄, Sb₂O₃, Sb₂O₄, Sb²O₅, GeO, GeO₂, Bi₂O₃, Bi₂O₄,Bi₂O₅, etc .; a conductive polymer such as polyacetylene, etc.;Li—Co—Ni-based material, etc.

[Separator]

A separator according to the present invention forms a radical unitthrough conducting a simple stacking process apart from a foldingprocess or a roll process to accomplish the simple stacking.Particularly, the attachment of the separator, with the cathode and theanode may be accomplished by melting a separator sheet itself by heat toaccomplish attaching and fixing in a laminator. From the above-describedprocess, a pressure is continuously maintained and a stable interfacecontact between the electrode and the separator sheet may becomepossible.

Any material that may exhibit insulating properties and have a porousstructure for the movement of ions may be used for the manufacture ofthe separator sheet or the separator interposed between the cathode andthe anode of a cell. The separator and the separator sheet may includethe same material or not.

For the separator or the separator sheet, for example, an insulatingthin film having a high ion transmittance and mechanical strength may beused. The pore diameter of the separator or the separator sheet iscommonly about 0.01 to 10 μm, and the thickness thereof is commonlyabout 5 to 300 μm. As for the separator or the separator sheet, forexample, an olefin-based polymer such as chemical-resistant andhydrophobic polypropylene, etc.; a sheet or a non-woven fabric obtainedby using glass fiber, polyethylene, or the like, may be used. When asolid electrolyte such as a polymer is used as an electrolyte, the solidelectrolyte may also function as the separator. Preferably, apolyethylene film, a polypropylene film, or a multi-layered filmobtained by combining the films, or a polymer film for a polymerelectrolyte or a gel-type polymer electrolyte such as polyvinylidenefluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidenefluoride hexafluoropropylene copolymer, may be used.

The electrode assembly according to the present invention may be appliedin an electrochemical cell producing electricity through theelectrochemical reaction of a cathode and a anode. Typical examples ofthe electrochemical cell include a super capacitor, an ultra capacitor,a secondary battery, a fuel cell, all sorts of sensors, an apparatus forelectrolysis, an electrochemical reactor, and the like. The secondarybattery is particularly preferred.

Secondary battery has a structure in which a chargeable/dischargeableelectrode assembly having an impregnated state with an ion-containingelectrolyte is built in a battery case. In a preferred embodiment, thesecondary battery may be a lithium secondary battery.

Recently, a lithium secondary battery attracts much concern as a powersource of a large size device as well as a small size mobile device. Alight weight lithium secondary battery may be preferred for applyingthereof in these fields. As one method of decreasing the weight of thesecondary battery, a built-in structure including an electrode assemblyin a pouch-type case of an aluminum laminate sheet may be used. Sincethe features on the lithium secondary battery are well known in thisart, the explanation on the lithium secondary battery will be omitted.

In addition, as described above, when the lithium secondary battery isused as the power source of a medium and large size device, a secondarybattery maximally restraining the deterioration of an operatingperformance for a long time, having good lifetime properties and havinga structure possibly being mass-produced with a lower cost, may bepreferred. From this point of view, the secondary battery including theelectrode assembly of the present invention may be preferably used as aunit battery in a medium and large size battery module.

A battery pack including a battery module including a plurality ofsecondary batteries may be used as a power source in at least one mediumand large size device selected from the group consisting of a powertool; an electric vehicle selected from the group consisting of anelectric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-inhybrid electric vehicle (PHEV); an E-bike; an E-scooter; an electricgolf cart; an electric truck; and an electric commercial vehicle.

The medium and large size battery module is constituted of a pluralityof unit batteries connected in a serial system or a serial/parallelsystem so as to provide a high output and high capacity. The techniqueson these features are well known in this art. Thus, the explanation onthe features will be omitted in this application.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

What is claimed is:
 1. A fabricating method of an electrode assemblycomprising: forming a radical unit having a four-layered structureobtained by stacking a first electrode, a first separator, a secondelectrode, and a second separator one by one; and stacking at least oneradical unit one by one to form a unit stack part.
 2. The fabricatingmethod of an electrode assembly of claim 1, wherein the radical unit isformed by attaching the electrode and the separator to each other. 3.The fabricating method of an electrode assembly of claim 2, wherein anattachment of the electrode and the separator is conducted bypressurizing the electrode and the separator, or by applying pressureand heat onto the electrode and the separator.
 4. The fabricating methodof an electrode assembly of claim 2, wherein the separator is coatedwith a coating material having adhesiveness.
 5. The fabricating methodof an electrode assembly of claim 4, wherein the coating material is amixture of inorganic particles and a binder polymer.
 6. The fabricatingmethod of an electrode assembly of claim 4, wherein both sides of thefirst separator facing the first electrode and the second electrode arecoated with the coating material, and one side of the second separatorfacing the second electrode is coated with the coating material.
 7. Thefabricating method of an electrode assembly of claim 4, wherein bothsides of the first separator facing the first electrode and the secondelectrode are coated with the coating material, and one side of thesecond separator facing the second electrode and an opposite sidethereof are coated with the coating material, the unit stack part beingobtained by stacking at least two radical units, the radical units beingattached to each other through the coating material of the secondseparator.
 8. The fabricating method of an electrode assembly of claim1, wherein the radical unit is obtained by repeatedly stacking thefour-layered structures.
 9. The fabricating method of an electrodeassembly of claim 1, further comprising stacking of first auxiliary uniton a first distal end electrode, the first distal end electrode beingthe first electrode positioned at an uppermost or a lowermost portion ofthe unit stack part, when the first electrode being an cathode, and thesecond electrode being a anode, the first auxiliary unit being formed bystacking from the first distal end electrode, the separator, the anode,the separator and the cathode one by one, when the first electrode beingthe anode, and the second electrode being the cathode, the firstauxiliary unit being formed by stacking from the first distal endelectrode, the separator and the cathode one by one.
 10. The fabricatingmethod of an electrode assembly of claim 9, wherein the cathode of thefirst auxiliary unit comprises: a current collector; and an activematerial coated only on one side facing the radical unit among bothsides of the current collector.
 11. The fabricating method of anelectrode assembly of claim 1, further comprising stacking a firstauxiliary unit on a first distal end electrode, the first distal endelectrode being the first electrode positioned at an uppermost or alowermost portion of the unit stack part, when the first electrode beingan cathode, and the second electrode being a anode, the first auxiliaryunit being formed by stacking from the first distal end electrode, theseparator, the anode, and the separator one by one.
 12. The fabricatingmethod of an electrode assembly of claim 1, wherein the unit stack partfurther comprises a second auxiliary unit stacked on a second distal endseparator, the second distal end separator being the second separatorpositioned at an uppermost or a lowermost portion of the unit stackpart, when the first electrode being an cathode, and the secondelectrode being a anode, the second auxiliary unit being formed bystacking from the second distal end separator, the anode, the separatorand the cathode one by one.
 13. The fabricating method of an electrodeassembly of claim 12, wherein the cathode of the secondary auxiliaryunit comprises: a current collector; and an active material coated onlyon one side facing the radical unit among both sides of the currentcollector.
 14. The fabricating method of an electrode assembly of claim1, further comprising stacking a second auxiliary unit on a seconddistal end separator, the second distal end separator being the secondseparator positioned at an uppermost or a lowermost portion of the unitstack part, when the first electrode being an cathode, and the secondelectrode being a anode, the second auxiliary unit being formed bystacking from the second distal end separator, the first cathode, theseparator, the anode, the separator and the second cathode one by one,the second cathode of the secondary auxiliary unit comprising a currentcollector and an active material coated only on one side facing theradical unit among both sides of the current collector.
 15. Thefabricating method of an electrode assembly of claim 1, furthercomprising stacking a second auxiliary unit on a second distal endseparator, the second distal end separator being the second separatorpositioned at an uppermost or a lowermost portion of the unit stackpart, when the first electrode being a anode, and the second electrodebeing an cathode, the second auxiliary unit being formed by stackingfrom the second distal end separator, the anode, the separator, thecathode, the separator and the anode, one by one.
 16. The fabricatingmethod of an electrode assembly of claim 1, further comprising fixing byusing a polymer tape for taping the side portion or the front portion ofthe unit stack part.
 17. An electrochemical device comprising theelectrode assembly obtained by the fabricating method according to claim1.